Seachem Zeolite is a naturally ocurring, highly-porous mineral that binds ammonia and heavy metals through an ion exchange mechanism. It has the highest ammonia binding capacity of any available zeolite - ten times higher than some products, and twice the capacity of the closest competitor. It also removes harmful metal ions like lead, copper, nickel, and zinc. Many zeolites deplete calcium levels in saltwater tanks, but Seachem Zeolite will actually supplement calcium by 10-15 mg/L. It won't increase general hardeness in freshwater tanks, where the ionic strength is low. Seachem Zeolite is supplied both as loose granules and in easy-to-use packets. Its fine-grain size provides the highest performance in the least amount of space.